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<title>无标题文档</title>
<script>

//3.变量的查找是就近原则去需找,var定义的变量,当就近没有找到的话，就会查找外层

/*var a = 10;

function aaa(){
	
	alert(a);   //undefined
	var a = 20;
	
}

aaa();*/

/*var a = 10;

function aaa(){
	
	var a = 20;
	alert(a);    //20
	
}

aaa();*/

/*var a = 10;

function aaa(){
	
	alert(a);    //10
	a = 20;
	
}

aaa();
*/

/*var a = 10;

function aaa(){
	
	alert(a);   //undefined
	var a = 20;
	
	
	/*var a;
	//alert(a);   //undefined  预解析
	//a = 20;
	
}

aaa();*/



var a = 10;

function aaa(){
	
	bbb();
	
	alert(a);
	
	function bbb(){
		var a = 20;
	}
	
}

aaa();


</script>
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